Crustal thickness variation from a continental to an island arc terrane: Clues from the gravity signatures of the Central Philippines

Issue Date

5-2015

Abstract

Offshore and ground gravity data were utilized to estimate crustal thickness across the Central Philippines where a transition from continental to island arc terrane occurs. Significant differences in gravity anomalies were observed between the Palawan Microcontinental Block (PCB) and the Philippine Mobile Belt (PMB), two major terranes that came together through arc-continent collision. Islands of the PCB (Mindoro, Tablas, Romblon, Sibuyan and western Panay), made up of an assortment of continent-derived sedimentary and igneous rocks and slivers of ophiolitic bodies, register lower Bouguer anomalies compared to that displayed by Masbate Island in the PMB. The calculated crustal thickness of this region exhibits a complex Moho topography of non-uniform depth across the collision zone with the thickest parts (~32. km) corresponding with ophiolitic units emplaced consequent to arc-continent collision. On the other hand, relatively thinner crust (~21. km) within the collision zone coincides with areas surmised to have undergone attenuation following intra-arc rifting. The same characteristics are observed offshore of western Mindoro and within the Marinduque Basin, areas known to have experienced crustal thinning following regional tectonic rearrangements that triggered riftings and intra-basin openings.

Source or Periodical Title

Journal of Asian Earth Sciences

ISSN

1367-9120

Volume

104

Page

205-214

Document Type

Article

Physical Description

maps, illustrations

Language

English

Subject

Central Philippines, Crustal thickness, Gravity

Identifier

https://doi.org/10.1016/j.jseaes.2014.08.031.

Digital Copy

yes

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